Dynamic Response Analysis Of Thin-Walled Lined Composite Pipe Under Impact Load

In long-term service,pipelines are prone to corrosion,aging and other problems,which bring hidden dangers to the safe operation of pipelines and require repair or replacement.At the same time,with the continuous improvement of structural safety requirements in countries around the world,the research on structural components is no longer limited to the static stage,the impact of impact,explosion,vibration and other dynamic loads on the structure has also attracted the general attention of scholars.Thin-wall lining repair technology adopts special construction technology to drag the lining pipe into the original pipeline and make it closely fit with the wall of the repaired pipeline,so as to improve the overall strength of the pipeline structure and extend the service life of the pipeline.The composite pipe repaired by this technology has structural particularity.Under dynamic load,the deformation of the composite pipe or the delamination of the lining layer will occur.It is of great significance to study the dynamic response characteristics and failure mode of the lining and the outer base pipe under impact load,so as to provide technical support for the thin-wall lining repair technology.In this paper,the vibration mode and natural frequency of the composite coffin were obtained through the excitation test of the composite pipe with thin wall lining.At the same time,the finite element analysis model was established based on the bilinear cohesion model with the help of ABAQUS software,and the dynamic characteristics of the composite pipe under the excitation force were analyzed.The analysis results are basically consistent with the test results.The bilinear constitutive model can be used to establish a numerical analysis model for the dynamic mechanical analysis of the interaction between layers of composite pipes.Established a finite element model of thin-walled lined composite pipes during the elastic deformation stage.By changing the impact force and pipeline parameters,the influences of impact velocity,interface bonding strength and lining thickness on the dynamic response and damage mechanism of the outer base pipe and lining were studied.The results show that when the mass of the impact material is small,the deformation of the pipeline and the elastic deformation stage,the damage of the thin-walled lined composite pipe is mainly concentrated at the interlayer interface.The interface bonding strength has a greater effect on the relative displacement of the interlayer,and the impact velocity and the thickness of the lining have a lesser effect on it.With the increase of bonding strength,the deformation coordination between the outer base pipe and the inner liner is improved,which increases the integrity and continuity of the composite pipe.At the same time,the relative displacement between layers decreases,the interlayer delamination trend is weakened,and the interface stiffness degradation rate decreases.With the increase of impact velocity,the difference of radial displacement between layers increases,and the interface stiffness degradation rate increases.With the increase of lining thickness,the radial stiffness increases and the radial displacement difference between layers decreases,which reduces the tendency of lining delamination.Established a finite element model of thin-walled lined composite pipes during the elastic-plastic deformation stage,lining thickness and other parameters were mainly considered.The failure mechanism and failure law of the thin-walled lined composite pipe were obtained.The results show that the thin-walled lined composite pipe will not only produce plastic deformation,but also "base lining separation" phenomenon between layers,resulting in local lining delamination.The impact velocity has a great influence.With the increase of impact velocity,the "base lining separation" phenomenon between the outer base pipe and the lining becomes more obvious,and the delamination area of the lining increases.There is a certain threshold value for the effect of interface bonding strength.When the interface bonding strength is less than 2.5 times of the original interface strength,the "substrate separation" phenomenon is weakened,the delamination area of the lining is greatly reduced,and the deformation coordination ability of the two is greatly improved.After 2.5times of interface bonding strength,there is basically no delamination failure between layers.The main failure of pipeline is the plastic deformation of pipe body.The effect of the thickness of the lining is similar to that of the interface bonding strength.Before the thickness is less than 2.5mm,the delamination failure of the lining decreases significantly with the increase of the thickness.After the thickness is more than 2.5mm,the effect of the increase of the thickness is no longer significant.The research shows that interlayer bonding strength and lining thickness are the main factors affecting the delamination of lining.When the construction technology is difficult to ensure the bonding effect,the thickness of lining can be appropriately increased to make up for it.